Secondary interior spaces that have been previously modified and lack important architectural features or finishes are usually less critical in defining a building’s importance. While these spaces still help define a building’s historic significance and character, they also provide more opportunities for changes necessary to convert a building to a new use. Such changes must not, however, alter the historic and architectural character of the spaces to the extent that they negatively impact the overall historic character and appearance of the property. (See related guidance on Changing Secondary Interior Spaces in Historic Buildings.)

Historically-finished secondary spaces that have been previously modified and lack important architectural features or finishes, but that remain finished spaces at the start of a project, still contribute to the overall historic character and appearance of a building. Once work is begun on these spaces—such as anticipatory demolition, removal of non-historic finishes, or installation of new plumbing or mechanical systems (whether to serve these or other spaces of the building)—the spaces must be returned to a finished character at the completion of the project. Removing interior finishes and leaving structural systems or components exposed in a building that had finished spaces historically, such as in a school, office building, or apartment building, will change the building’s character and give it an appearance it never had historically, and, therefore, will not meet the Secretary of the Interior’s Standards for Rehabilitation (the Standards).

The examples below address some common problematic issues concerning unfinished conditions in secondary spaces of otherwise completed rehabilitation projects submitted for final certification (Part 3). Such work—whether the result of planned work not yet undertaken (e.g., a tenant space without a tenant), work not undertaken as approved in the Part 2 application, or work with unplanned effects (e.g., new plumbing or mechanical equipment serving the floors above that is not concealed within interstitial spaces, as originally proposed, and left exposed)—can cause a project to not meet the Standards. This work should be anticipated, planned for in advance, and coordinated during construction to avoid any issues at project completion. Otherwise, certification of a project may be jeopardized or remedial work may be required for a project to be certified.

Unless otherwise noted, the examples assume that the space being described is a historically-finished secondary space that was previously modified, lacks important architectural features or finishes, and remains a finished space at the start of the project. Further guidance and examples can be found using the Preservation by Topic index.

Removing plaster or other finishes to expose portions of brick or stone walls, structural elements, or ceilings in historically-finished, upper-story secondary spaces will, in general, negatively impact the overall historic character of a property. Exposing portions of walls, ceilings, or other features, whether on a single floor or scattered throughout the building, or creating a distressed or deteriorated appearance is unlikely to meet the Standards and may therefore require remedial work for a project to be certified.

Depending on the character of the building, the relative importance of the secondary space(s), and the extent to which all the other completed work meets the Standards, there may be instances that such work, if discrete and limited, may not preclude the overall project from meeting the Standards. In such instances, for example, the treatment should be limited and incidental in the context of the secondary spaces and the overall project, not affect the appearance of any nearby important historic features or materials, and generally not be highly visible from the exterior of the building or from primary interior spaces or non-historic public areas.

Example 2. New mechanical, electrical, and plumbing (MEP) systems in secondary spaces that were historically finished.

New MEP systems in historically-finished secondary spaces, whether to serve the spaces themselves or adjacent spaces, should generally be concealed in order to preserve the historic character and appearance of the spaces and the building. Using existing soffits, chases, shafts, and interstitial spaces, where possible, is recommended. Constructing similar new features may also be possible without negatively impacting the historic character of the space or creating new features readily visible at windows from the exterior of the building. Examples include creating a new soffit in a secondary space behind a corridor wall to accommodate new HVAC ductwork or lowering a flat ceiling several inches, but still above the top of window openings, in order to accommodate new plumbing or ductwork.

In other instances, some exposed new plumbing such as a sprinkler system or mechanical ductwork may have less impact on the historic character of a secondary space and the overall building than concealed plumbing and ductwork—if painted, simply configured, and sensitively designed, sized, and located to be as visually unobtrusive as possible. [This may be true as well for secondary spaces that do retain historic features and finishes, such as those with expressed structural systems or highly ornamented plaster ceilings.]

For example, installing a large soffit in a secondary space may more negatively impact the historic character and appearance of a space than exposed plumbing or ductwork if it is sensitively designed and located. Similarly, lowering a ceiling to accommodate new plumbing or ductwork, depending on the depth required, could change character-defining ceiling heights of the building or proportions of the space. Also, lowering a ceiling below the top of the windows could create soffits visible from the exterior of the building and impacts its appearance.

Exposing ceiling penetrations in a secondary space in order to accommodate plumbing for the floors above can negatively impact the historic character of the space and the overall building. New ceiling penetrations must almost always be concealed. Even in secondary spaces that lack important architectural features and finishes, exposed ceiling penetrations, unless very few and very visually unobtrusive, will rarely meet the Standards because of their impact on the character and appearance of the space and the overall building.

Example 3. “White box” condition in secondary (tenant) spaces that were historically finished and for which a tenant has yet to be identified.

The rehabilitation of historically-finished secondary spaces as part of an overall rehabilitation project, even when the spaces lack important architectural features or finishes, must still be carefully planned and considered. Once features, finishes, and materials have been removed from such spaces as part of a project, the spaces must generally be returned to a finished condition at completion of the project for the historic character of the spaces and the overall property to be preserved. In most such instances, a “white box” condition with a finished ceiling, walls prepped for painting, and concealed electrical and mechanical systems (even if how the systems are concealed is temporary until the actual tenant build-out) will be necessary to return a space to a finished condition necessary for Part 3 certification.

In some limited instances, leaving a secondary (tenant) space unfinished, such as one in a large, multi-story downtown office building, may not negatively impact the overall historic character of a building and the ability for a Part 3 certification to be issued. Conversely, an unfinished tenant space in a smaller building, such as a secondary (tenant) space on the second floor of a small two-story Main Street commercial building, would generally have a greater impact on the historic character of the building and likely preclude certification.

In the context of an overall project that otherwise meets the Standards, the extent of any unfinished conditions in such secondary spaces must be minor, not highly visible, and relatively incidental in the context of the specific floor(s) of the building, and the overall building generally. In all instances, other work that has been undertaken in the space(s) (e.g., completed mechanical ductwork and ceiling penetrations as described in the above examples) must be consistent with the description of work approved as part of the Part 2 application for the project. Once a use or tenant has been identified for the space, the proposed tenant build-out must be submitted for NPS review if it is to be undertaken within five years of completion of the project.

[Ground-floor tenant spaces are generally not considered to be secondary spaces, but this “white box” example may be true as well for such spaces that were similarly historically finished spaces but previously modified, lack important architectural features or finishes, and remain finished spaces at the start of the project.]